Adaptation of sighting telescopes for nocturnal use



L. FRANZ ADAFTATION 0F SIGHTING TELESCOPES FOR NOCTURNAL USE Filed June 25, 1921 INVENTOR Luuw|e Franz.

Patented Feb. 17, 3.925.

UNITED STATES PATENT DFFICE.

1 LUDWIG FRANZ, or

MUNICH, GERMANY, ASSIGNOE TO THE FIRM C. A. STEINHEIL S6HNE, OF MUNICH, BAVARIA, GERMANY.

ADAPTATION OF SIGHTING TELESCOPES FOR NOCTURNAL USE.

Application filed June 25, 1921.

Serial No. 480,389.

TFRANTED UNDER THE PBOVISIG'NS (D3 TH ACT 0F MARCH 3, 1921, 41 STAT. L. 1313.)

To all whom it may concern:

Be it known that I, L'oowro. FRANZ, a citizen of the Republic of Germany, residing at Munich, Bavaria, Germany, have invented certain, new and useful Improvements Relating to the Adaptation of Sight- 7 ing Telescopes for Nocturnal Use, of which the following is a specification, and for which I have made application in Germany filed June 28, 1918, under N0. St. 31297IX/42h.

- Aiming telescopes for tire-arms have long been generally known; they are intended to secure accurate firing in daylight or possibly in twilight. For hunting at night or in the dusk night aiming devices as described in my patent application No. 480,39 filed June 25, 1921, are best adapted; they require therefore no further description here. Both of these devices can be used with one and the same fire-arm; this was made possible heretofore by making those parts ofthe aiming telescope and of the night aiming device, which served to connect the same to the gun, exactly similar in both devices. Such an arrangement has however the great disadvantage, that two separate devices are necessary, which is both inconvenient and expensive. The present invention unites both devices in one and the same apparatus. The general idea of the invention is as follows:

In the image-plane of the objective of an aiming telescope a dark aiming-mark is so arranged, that it shows the striking point of the bullet in an image of the object aimed at, said image being projected by the objective. To convert an aiming telescope into a night aiming device, the image of the incandescent cross-line of the night aiming device must obviously be arranged to occupy the exact position of the aiming mark of the aiming telescope, since the point of intersection of the cross-line also coincideswith the striking point of the bullet. The aiming mark of the aiming telescope will however then totally or partly intercept the light coming from the incandescent cross-line, especially the light from that part of the cross-line which is indispensable for the purpose .of aiming. This necessitates the removal of the aiming mark out of the different ranges.

image-plane when converting the aiming telescope into a night aiming device. The present invention refers to means by which this result can be attained.

The aiming mark of an aiming telescope is measurably movable for adjusting it to This delicate adjusting and measuring device may not be interfered with by the removal of the aiming mark and this indispensable requirement constitutes the chief difiiculty in converting an aiming telescope into a night-aiming device. The means employed to secure this conversion can be different, according to the type of the aiming telescope in question; but they all have the same end in view, name-- ly to avoid a disturbance of the accuracy of the aiming-telescope through the con ersion.

The aiming telescope with lens reversing system has two image-planes, namely the front-image plane of the objective and the being at the same time substituted for the eye-piece, thus converting the aiming telescope into the best and most usual type of night aiming device. The aiming marl: of the aiming telescope, however, here obstructs the rays coming from the incandescent cross-line, since the image of the latter is projected by the reversing system directly onto said aiming mark, being thereby partly extinguished. In this case the present invention removes the obstruction by shifting the aiming mark (generally in a downward direction) in the image plane itself so far out of the path of the rays coming from the incandescent cro s-line. that the latter can pass without hindrance.

.This shifting of the aiming mark can conof view of the aiming wise the beam ofdiii-used light of the night rule therefore on the upper side). In the case of this conversion it is further necessary to make the diaphragm 1n the image plane of the objective lar er than the field telescope, as otheraiming device would be obstructed. The field of view must therefore be'limited by a diaphragm in the image-plane of the eye piece, said diaphragm being removable with the e e-niece. since it lies directl T in the I markout of the image plane;

' 2. The optical displacement of the imageplaneoutoi the plane of the aiming mark. Referring to means 1: I p

In contradistinction tothe usual rigid connection of the measuring and adjusting device with the aiming mark, the present invention in this case makes the aiming markremovable from the adjusting device. The simplest and most: reliable means is the shifting of the aiming mark in the direction ofthe optical ,aXis in order tomake room for the lamp. The measuring and adjusting device can also be-designed to be bodily removedand its place taken by the lamp- It is obvious, that these mechanical interchangements can also be applied to night-,aiming devices with, a lens reversing system.

Referring to means-2: The present inventionin this case introduces a positive or negative lens, by thedisplacement of which in an axial direction theimage-plane of the objective is removed so far from the plane ofthe aiming mark, thatthe eii'ect of the-latter on the rays ofithe night. aiming device is negligible. Here also it is necessary to make the diaphragmfor the fieldof view removable with the eye-piece.

The accompanying drawings represent the present invention in several different adaptations together with details. fTo avoid unnecessary. complications the drawings are diagrammatic and show only those parts which are essential to the present invention. Fig. 1 shows the optical, parts and the ray paths of an aiming telescope with lens reversingthe system, in which the planes and (Z. at right angles to the optical axis, represent thetwo image planes of the aiming telescope. Fig. 2 shows this telescope a concave mirror 3.

cation .No. 480,390, filed converted into a night aiming device; the lamp l'has been introduced into. the image plane (Z and the eye-piece exchanged for Figs. 3 and a show types of aiming. marks for use here with the aiming telescolaesgihe image of the incandescent cross-line of the projector lamp of the night aiming device is here indicated by dotted lines. In Fig. 5 an aiming telescope with a prism or mirror reversing system is shown, in which a negative lens 6 has been arranged in close proximity to the image-plane c. F ig. 6 shows this. telescope convertedinto .a night aiming. device by shifting-the lens 6 the image-plane has been displaced. Figs-7 andf8n'show similar devices toFigs. 5 and 6, butinsteadtof a negative lens a-positive lens 13 has here been introduced.

The following. denominations are common to allthefigures :.1 is theelectriclamp of the night aiming device; ,2 an objective, which in the case of an aiming telescopeprojects an image of the'object aimed at in'the plane. of the aiming mark,- whereas. in thecase ofa'night aiming-device it projects he incandescent.cross llne.of the lamp onto the ob ect aimed at; '3 is the concave mirror ,ofthe night aiming. device adapted to create a. beam of diffused light 0 is the imagevplane of the aiming-mark, at right angles to an ,opticalaxis; d is the image-plane or the,

lamp ofthe night-aiming device, also at right angles to the optical axis. 7

In the following the several figures will be described in detail. The principle or the aiming telescope is generally known and.

needs no further description; the night aiming deviceis described in my patent appli- June25, 1921, to which I hereby refer.

Accordingto F ig. l the objective 2 produces an invertedimageof the object aimed at in the image-plane o, inwhich anaiming mark similar toFig. 3 or 4 is arranged. The

lens reversing system 4: then projects this image uprighttogether with the aiming mark in the image-plane (Z, in which both .can be simultaneously viewed through the astronomical ByQ PIGCG i A diaphragm-7 is rigidly connected with the eye-piece 5,

.saiddia-phragm limitingtlre field of view-of.

the aiming telescope-and being detachable with the eye-piece; In order to convert this aiming telescope into a night: aiming device (Fig. 2) t'lieeye-"piece 5'is removed and the concave. mirror .3 attached in its place;

the lamp. l-is then inserted in the imageplane d. The reversingsystema now pro duces an mage of the incandescent crossline ofthe lamp in the image-plane c, where it will coincide with the position of the aiming mark when the latter is in the position for firing, because. this aiming mark is adjusted to cover the same point of the target as the incandescent cross-line of the lamp. In the case of an almmg-mark of the form 8 3) only the horizontal adjusting device a somewhat greater range of movement downwards. The aiming mark according to 8 (Fig. 3) is to be given the preference, as here only a very small part of the vertical thread is darkened, Whilst in the case of an aiming mark according to 9 (Fig. 4) the whole of the lower half of the vertical thread disappears.

The position of the incandescent cross-line 10 when using the instrument as a night aiming device is indicated by dotted lines in Figs. 3 and 4. Figs. 1 and 2 are typical of the device according to the present invention.

Fig. 5 shows the optical parts of the well known prism aiming telescope, a negative lens 6 being introduced and arranged quite near to the image-plane c of the objective, said negative lens having in this position hardly any ettect on the optical rays. The objective 2 projects an image of the object aimed at, which is reversed by the mirror reversing system 11,12, so that it can be viewed together with the aiming mark through the astronomical eye-piece The diaphragm 7 for limiting the field of view must here also be connected to and detachable with the eye-piece 5. because for the night aiming device a larger aperture than said diaphragm is required in the plane 0. In order to adapt the device for use as a night aiming device the negative lens 6 is shifted from to 2', thereby displacing the image-plane from c to (l and at the same time increasing-the focal distance of the objective. The lamp 1 can now be inserted in the image-plane (Z and at the same time the eye-piece exchanged for the mirror 3.

The aiming mark, for instance Fig. 3, being wards. Figs. 7 and 8 represent the same device as Figs. and (3, the reversal of the image being however here produced by a positive lens 13; when the device is in use as an aiming telescope, this positive lens 13 must of course be in the plane 2', thereby reducing the focal distance of the objective 2; to adapt the device for use as a night aiming device said positive lens 13 is shifted to 0 where it will exert less influence on the ray paths; the image-plane is hereby displaced from 0 to (Z and the focal distance of the apparatus increased. In all other respects this form of the device is similar to Figs. 5 and 6.

IVhat I claim as my invention and desire to secure by Letters Patent is:

1. The herein described method of converting an aiming telescope with an aiming mark in the image plane of the objective into a night aiming device, which consists in introducing a lamp of a night aiming device into the image plane of an eye piece of the telescope, and arranging a concave mirror of a night aiming device in place of said eye piece.

2. The herein described method of converting an aiming telescope with an aiming mark in the image plane of the objective into a. night aiming device, which consists in making a beam of light issuing from a lamp disposed in the image plane of an eye. piece reflect in a concave mirror arranged in the plane of said eye piece, and producing an image of an incandescent cross line of said lamp in an image plane disposed in advance of said lamp by means of a reversing system disposed between the lamp and said last named image plane.

3. The arrangement of elements in an aiming telescope to produce a night aiming device of the character described, which comprises an objective and a lens reversing system, an image plane disposed between said objective and reversing system, a con cave mirror arranged in the place of an eye piece in said telescope, and a lamp having an incandescent cross-line which produces an image in said image plane, said lamp being arranged in the image plane of said eye piece it the latter were present.

In testimony whereof I hereunto afiix my signature in the presence of two witnesses.

IJUDWIG FRANZ. IVitnesses D. NIWELF S'rnixnnm, MICHAEL CHAYE. 

